Snes9x.com

Fresh install of Windows 10 x64, using two Xbox one controllers plugged in using USB to the computer. Controller drivers installed without any issues, so I went ahead and installed SNES9x 1.53 and set the controls up for the first controller, no problems. Loaded up Super Mario World, controls worked fine. So I went ahead and configured the 2nd controller, no problems setting the controls, but whenever I try to play 2 players on Super Mario World, the 2nd controller doesn't work. I loaded up a different game, Super Mario Kart, 2nd controller worked fine. What would cause some games not to work with 2 controllers?

Thanks